I'm writing a book, and a a portion of it involves a society of humanzees. Now, is there any plausible way that a hybrid (such as a humanzee) could procreate either with one another, or with their father/mother species? I apologize for my lack of understanding of biology, any help would be much appreciated!
This is a hypothetical scenario which I think could be compared in parallel to hybrids like a mule (offspring of a male donkey and a female horse) or a hinny (offspring of a male horse and a female donkey) or zebroids (reference). In the case of the fertility of mules on wikipedia it is stated that
A few female mules have produced offspring when mated with a purebred horse or donkey.
with examples being given as
Since 1527 there have been more than 60 documented cases of foals born to female mules around the world. There are reports that a mule in China produced a foal in 1984. In Morocco, in early 2002, a mare mule produced a rare foal. In 2007 a mule named Kate gave birth to a mule son in Colorado. Blood and hair samples were tested verifying that the mother was a mule and the colt was indeed her offspring (reference).
In the case of a hinny fertility is much more rare but there is a documented case on Wikipedia
In China in 1981, a hinny mare proved fertile with a donkey stallion. When the Chinese hinny was bred to a donkey jack, she produced "Dragon Foal," who resembled a donkey with mule-like features (reference).
The wikipedia page on hybrids will also be of interest in your research. In short, hybrids can procreate and give birth in rare cases. However, I wouldn't vouch on the survivability of the offsprings. Since your work is fictional, it is entirely left to your discretion on that topic. Btw, humazee or humzee makes a more intriguing name maybe. Good luck with the book.
Recent genetic analysis of human DNA shows neanderthal ancestry, so inter-species breeding to produce reproductively viable offspring (humanderthals?) appears to be possible - at least between species of the same genus. But with Homo sapiens being the only extant species in the genus Homo you'd be really stretching the boundaries of plausibility to have a human/ape or human/monkey hybrid.